The present invention relates to an exhaust passage component used for constituting an exhaust passage for conveying combustion exhaust generated in a combustion apparatus out of the apparatus.
For example, as disclosed in Japanese Unexamined Patent Application Publication No. 2009-92286, a hot water supply apparatus of latent heat recovery type is known, which includes a primary heat exchanger for recovering mainly sensible heat from combustion exhaust, and a secondary heat exchanger for recovering mainly latent heat from the exhaust, a temperature of which has decreased as a result of heat exchange in the primary heat exchanger.
In this type of hot water supply apparatus, as the temperature of combustion exhaust in the secondary heat exchanger decreases, a relative humidity of combustion exhaust becomes significantly high. This results in production of condensed water (drainage water) within the exhaust passage. Therefore, a drainage discharge pipe is provided to drain the condensed water, and a neutralizer or the like is also provided to neutralize acidic condensed water.